Present methods and apparatus for the mixing of blood plasma and additives in a process of fractionation have several important shortcomings. In the methods and apparatus of the art existing prior to the present invention, the plasma or supernatant is cooled in large jacketed vats. The amounts vary from one fractionator to another and several thousand liters can be involved at one time. Additions are slowly metered and mixing is achieved by stirring.
This process can taken several hours. The heat of solution is removed by a refrigerant which is circulated through a jacket surrounding the vat. There are several problems associated with this method of mixing. At the beginning of the procedure, there is an imbalance in the mix with the high concentrations of the additives being in localized spots in the vat. This can cause denaturization of the proteins and possible precipitation of unwanted proteins. The high concentrations of alcohol will cause a heat problem and possible denaturization of the proteins. In addition, the mixing process takes an extensive period of time, as long as 6 hours, and the whole batch of plasma is subjected to long-term alcohol denaturization, pyrogens and other possible damage that can cause the loss of the entire batch. Further, large batches of proper additives must be pre-cooled in order to help control the heat of solution.
Each batch of supernatant must be stored in refrigerated vats while waiting for the next fraction to be run. The whole process of batch fractionization is slow and cumbersome, requires many refrigerated vessels and requires constant attention and adjustment and many man-hours. Still another problem associated with batch mixing and handling is that frothing and bubbles can cause denaturization of the proteins that should be avoided. The system of automatically blending and handling plasma as described herein completely eliminates frothing.